【作者】 赵宇辉；

【导师】 程军；

【作者基本信息】 中北大学 ， 材料加工工程， 2006， 硕士

【摘要】 微观组织数值模拟对金属材料的发展和应用具有重要意义,也是计算材料科学领域的主要发展方向之一。利用计算机数值模拟技术对铝合金微观组织的形成过程进行模拟,可以优化工艺,提高铸件质量,具有很高的实用价值。用相场方法进行微观组织模拟是金属凝固过程模拟仿真的研究热点之一。本文采用相场法对铝合金铸件的枝晶生长过程进行了数值模拟,研究了不同模拟条件下的枝晶生长方式,探讨了其枝晶生长机制。本文以金属凝固理论为基础,推导了二维铝铸件微观组织的相场模型;基于均匀网格的有限差分法,编制了铝枝晶生长的相场法数值模拟程序;研究了各向异性常数、热扰动、初始晶核半径、过冷度等因素对枝晶生长形貌的影响。本文以Visual Fortran 6.0编程语言为软件开发工具,开发了基于Windows 2000环境下运行的具有自主权的模拟程序。该程序能够较好的模拟铝及铝合金铸件的微观组织枝晶生长方式。数值模拟的计算结果表明,相场方法凝固微观组织数值模拟可以再现与经典理论相一致的各种凝固特征。为了验证数值模拟结果的正确性,进行了浇注实验。得到的实验结果与计算机数值模拟基本一致,表明相场法模拟符合实际的枝晶生长现象,验证了本文相场模型所开发程序的正确性。更多还原

【Abstract】 Microstructure numerical simulation has important signification to the development andapplication of metal material,and also it is one of the mostly direction in the domain ofmaterial science.Modeling of microstructure formation using computer numerical simulationwill help to evaluate the castings processing technology so as to improve theirquality . Therefore microstructure formation simulation using phase-field method hassignificant practical merit. phase-field method is one of the hotspots of the numericalsimulation during solidification processes at present.In this paper,the dendrite growth of puresubstance and aluminum alloy are simulated using phase-field method.the dendrite growthbehaviors under the different conditions are finely studied,and the mechanism of the dendritegrowth is discussed.Based on the theory of metal solidification,The phase-field models of pure substance isderived successfully used to set up a two-dimensional mathematics in consideration of theinterface anisotropy and noise.The phase-field simulation program of the dendrite growth iscompleted on the basis of the Finite Difference method with uniform grids.The dependenceof simulation results on the anisotropy , disturbing, the initial nucleus radius andundercooling studied,and how to choose the values of these parameters is settled.Based on the windows 2000,Visual Fortran 6.0 has been used to set up this simulationsystem.This system can be used to simulation the dendrite growth behaviors of puresubstance and aluminum alloy.The result is consistent with the classic theory of solidificationmold-filling experiments are conducted to verify the simulated results and they are ingood agreement. The calculated results show that the phase-field method is more consistentwith the practical growth phenomenon and justified that our application programs.更多还原